The invention relates to a frequency changer protection circuit for controlling the acceleration of an electric vehicle. More particularly, the protection circuit enables to protect the motor and reduce current losses during the acceleration operation of the electric vehicle.
The control of electrically-driven (or electric) vehicles is presently achieved via simple control and protection circuits which time constant is usually excessively high to provide an adequate reaction. In critical situations such as motor starting or slope climbing, the control circuit can be damaged. In other situations when the acceleration control is not sufficient, a needed power may be increased or the acceleration may be instable.
It is therefore a principal object of the invention to provide a frequency changer protection circuit for controlling the acceleration of an electric vehicle that can overcome the above problems.
In accordance with the above and other objectives, the protection circuit of the invention arranges specific amplification curves with a sensor unit to render safer and more comfortable the control of the speed rate change of the motor during acceleration operations, meanwhile reducing current losses. A protection of the electric circuitry is thereby favorably achieved.
In accordance with the above and other objectives, the protection circuit of the invention further includes a control unit that automatically limits the outputted power to a maximum normal rated power of the motor, thereby protecting the motor and the control circuit meanwhile reducing losses of power during motor starting. The endurance of the motor is thereby increased.
In accordance with the above and other objectives, meanwhile achieving a limitation of the outputted power, the protection circuit of the invention further increases a frequency so as to increase the rotation speed of the motor, useful in motor starting and slope climbing.
To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention.